Method and apparatus for resistive power distribution

ABSTRACT

An electrical power distribution method and apparatus are disclosed, the apparatus comprising a first power distribution member section receiving electrical power from a power supply and a second high resistivity power distribution member section, electrically connected to the first section for supplying the electrical power to an electrical device in electrical communication with the high resistivity section.

CROSS REFERENCE TO RELATED APPLICATIONS

This patent application is a continuation of U.S. patent applicationSer. No. 11/857,550 by John B. Janik, entitled Method And Apparatus ForResistive Power Distribution, which is incorporated herein by referencein its entirety.

FIELD OF THE DISCLOSURE

The present disclosure relates to the field of electrical powerdistribution.

BACKGROUND OF THE DISCLOSURE

Electric power is essential to a modern industrial plant or ship'sfunctional effectiveness. Electric power steers the ship, operates theship's rudder hydraulic system, sensitive navigation systems, dynamicpositioning systems, runs auxiliary systems for cooking and cleaning andprovides light and power to interior systems. An industrial plant orship without electric power is useless for its operational mission orpurpose. The primary power distribution voltage, phase, and frequencyused on many U.S. and international vessels are three-phase 50 or 60 Hzat 450-600 Volts AC. Secondary voltage, phase, and frequency are 120-240Volts, single or three-phase, 50 or 60 Hz. The secondary voltage isderived from the primary voltage system through transformer banks andcircuit breakers. Lighting distribution systems are 120-240 V, single orthree-phase, 50 or 60 Hz and are supplied from the primary powercircuits to transformer banks.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts an illustrative embodiment of a power distribution systemusing a resistive member to supply power to an electrical device;

FIG. 2 depicts a voltage notch and voltage spike power disturbance in analternating current supply voltage;

FIG. 3 depicts an illustrative embodiment of a power distribution systemusing a resistive member to supply power to a voltage source alternatingcurrent drive with integral capacitor;

FIG. 4 depicts an illustrative embodiment of a power distribution systemusing a low resistivity member surrounding a high resistivity centermember;

FIG. 5 depicts a flow chart of functions performed in anotherillustrative embodiment; and

FIG. 6 depicts a flow chart of functions performed in anotherillustrative embodiment

DETAILED DESCRIPTION

In another particular embodiment, an electrical power distributionapparatus is disclosed, the apparatus comprising a first powerdistribution member section for receiving electrical power from a powersupply; and a second high resistivity power distribution member sectionhaving a resistivity higher than the first section and electricallyconnected to the first section for supplying the electrical power to anelectrical device. In another particular embodiment of the apparatus,the apparatus further comprises an electrical device in electricalcommunication with the second section, wherein the second sectionreduces a current to the electrical device. In another particularembodiment of the apparatus the apparatus further comprises theelectrical device is an electrical circuit breaker receiving power fromthe second section during an electrical short circuit on a load side ofthe electrical circuit breaker.

In another particular embodiment of the apparatus, the first section hasa resistivity of approximately one half of the resistivity of the secondsection. In another particular embodiment of the apparatus, the firstsection is made of copper and the second section is made of steel. Inanother particular embodiment of the apparatus, the first section andthe second section have resistivity approximately equal to twice theresistivity of copper. In another particular embodiment of theapparatus, at least one of the first section and the second section is abus. In another particular embodiment of the apparatus, at least one ofthe first section and the second section is a cable. In anotherparticular embodiment of the apparatus, the second section forms anelectrical filter with a capacitance of the electrical device forsmoothing electrical disturbances in the electrical power supplied tothe electrical device.

In another particular embodiment of the apparatus, the electrical deviceis a device selected from the group consisting of an uninterruptablepower supply and an alternating current drive for a variable speedalternating current motor. In another particular embodiment of theapparatus, the electrical disturbances are one selected from the groupconsisting of a voltage spike and a voltage notch. In another particularembodiment of the apparatus, the second section comprises a centersection and the first section comprises a low resistivity outer membersurrounding the center member, wherein the low resistivity member formsan inductor around the center member so that the low resistivity memberpresents a high reactance to high frequency voltages substantiallyhigher than 60 Hz, so that the high frequency currents pass through thecenter member and experience a current reducing voltage loss. In anotherparticular embodiment of the apparatus, low frequency electrical powerof approximately 60 Hz sees a low reactance on the low resistivity outermember and travels through the inductor low resistivity outer member. Inanother particular embodiment of the apparatus, the apparatus furthercomprises the low resistivity outer member has a resistivity ofsubstantially one half the resistivity of the high resistivity centermember.

In another particular embodiment of the apparatus, the low resistivityouter member is made of copper and the high resistive center member ismade of steel. In another particular embodiment of the apparatus, anouter high resistivity member surrounding the low resistivity member andthe center member. In another particular embodiment of the apparatus,the apparatus further comprises a conductive connector at each end ofthe cable, wherein the conductive connectors form an electricalconnection between the high resistivity center member, the outer lowresistivity member and the outer high resistivity member, wherein lowfrequency current at substantially 60 Hz flows through the outer lowerresistivity member and high frequency currents above 1 KHz flow thoughthe high resistivity center member.

In another particular embodiment of the apparatus, the high resistivitycenter member and the high resistivity outer member form a magnetic fluxpath for magnetic flux generated by current flowing in the low frequencysurrounding member. In another particular embodiment of the apparatus,the apparatus further comprises a first power distribution membersection for receiving electrical power from a a second high resistivitypower distribution member section having a resistivity higher than thefirst section and electrically connected an electrical device inelectrical communication with the second section. In another particularembodiment of the apparatus, the second section comprises a centermember and the first section comprises a low resistivity outer membersurrounding the center member.

In another particular embodiment an electrical power distributionapparatus is disclosed, comprising an outer high resistivity membersurrounding the low resistivity outer member and the center member. Inanother particular embodiment a method for distributing electrical poweris disclosed, the method comprising receiving the electrical power on alow resistivity member; and supplying the electrical power to anelectrical device through a high resistivity member. In anotherparticular embodiment of the method, the high resistivity member has aresistivity that is substantially twice the resistivity of the lowresistivity member. In another particular embodiment of the method, atleast one of the high resistivity member and the low resistivity memberis a bus. In another particular embodiment of the method, at least oneof the high resistivity member and the low resistivity member is acable.

Turning now to FIG. 1, in an illustrative embodiment a powerdistribution apparatus is provided having a low resistivity powerdistribution member section (low resistivity section) 108 and a highresistivity power distribution member section (high resistivity section)106. The power distribution members can be an electrical powerdistribution bus or electrical power distribution cable. The powerdistribution members can also be a combination of a bus and a powercable, wherein either the high resistivity member section is a cable ora bus and the low resistivity member section is either a cable or a bus.In another embodiment, the power distribution member can be any type ofelectrical power distribution apparatus now known or unknown.

In another particular embodiment, the high resistivity section hassubstantially higher resistivity that is, around twice as muchelectrical resistivity than the low resistivity section. In anotherparticular embodiment the high resistivity section has less than twicethe resistivity of the low resistivity section. In another particularembodiment the high resistivity section has more than twice as muchresistivity as the low resistivity section. In another particularembodiment, the high resistivity member section has a resistivity thatis twice the resistivity of the low resistivity member section. The highresistivity power distribution member section and the low resistivitypower distribution member section are electrically connected so thatpower applied to the low resistivity power distribution member sectionis transferred to the low resistivity power distribution member section.In another illustrative embodiment, the low resistivity member sectionis made of copper and the high resistivity member section is made ofsteel. In another illustrative embodiment, the high resistivity membersection is made of stainless steel. In another illustrative embodiment,the high resistivity member section is made of a nickel alloy. Inanother illustrative embodiment, the high resistivity member section ismade of another alloy. In another illustrative embodiment, the highresistivity power distribution member section is made of any materialthat manifests sufficient resistivity, higher than a resistivity for alow resistivity power distribution member section to perform thefunctions disclosed herein and operate according to the parentdisclosure.

In another illustrative embodiment structures such as cables and busesmade of high resistivity materials such as steel, are used to replacestructures that are made of low resistivity materials such as copper.The making of a structure in a high resistivity material transforms alow resistivity structure into a high resistivity structure. Thus aparticular bus or cable having particular dimensions and made of lowresistivity materials such as copper can be manufactured to the samedimensions using a high resistivity such as steel thus enablingreplacement of the low resistivity structure with a high resistivitystructure. In particular illustrative embodiment the high resistivitystructure can be used in place of the low resistivity structure therebyproviding a higher resistance structure having the same dimensions inplace of the low resistivity structure having the same dimensions. Inanother embodiment, the low resistivity materials have a higherinductance than the high resistivity materials.

For purposes of illustration, FIG. 1 discloses a power distributionapparatus, which in another embodiment is a bus having a highresistivity section and a low resistivity section. In another embodimentthe power distribution member can also be a power distribution cablehaving a high resistivity section and low resistivity section. Inanother particular embodiment the power distribution apparatus can be asingle section bus or cable having a high resistivity, i.e.,substantially twice the resistivity of copper. Resistance andresistivity are used as closely related terms in this disclosure, as ahigh resistivity material is used to manifest a high resistance and alow resistivity material is used to manifest a low resistance for acable or bus having the same dimensions. In a particular illustrativeembodiment, a particular bus or cable made of copper (low resistivity,thus low resistance) can be replaced by a cable or bus made of steel(high resistivity, high resistance) having the same dimensions butproviding twice as much resistance. As shown in FIG. 1, the highresistivity bus section 108 provides power to at least one electricaldevice. For purposes of illustration the power generators 102 supplyalternating current power through the low resistivity bus section to thehigh resistivity bus section. In another embodiment the low resistivitybus section supplies DC power to the high resistivity bus section.

In another illustrative embodiment, alternating current power generators102 are connected to the low resistivity bus section 108 though circuitbreakers 104. In this example, circuit breakers 104 are relativelylarge, i.e., rated at 600 volts 2000 amps continuous. In anotherillustrative embodiment, a feeder (smaller) circuit breaker 105 rated at800 amps continuous connects a still smaller circuit breaker 107 to aload. Another embodiment is useful for all breaker voltage ratings. Thebreaker 107 is rated at 100 amps continuous in the present example ofFIG. 1. In the example of FIG. 1, the load 114 is powered from a motorcontrol center 110 which contains circuit breaker 107. Power is suppliedthrough the high resistivity power distribution bus member 106 to thefeeder breaker 105 and circuit breaker 107. One or more circuit breakers107 are provided within the motor control center to connect to loads114. In an illustrative embodiment all of the circuit breakers,including the circuit breakers 107 are also rated for a faultinterrupting current. Fault interrupting current is the amount ofcurrent that a circuit breaker is able to interrupt during a faultcondition such as an electrical short circuit. Fault current ratings mayrange widely for each of the circuit breakers. Fault current ratings canbe specified in kilo amps of interrupting current (KAIC) and can rangefrom 10 KAIC, 25 KAIC, 40 KAIC, 50 KAIC, 65 KAIC, 85 KAIC and 100 KAIC,etc.

As shown in FIG. 1, a short circuit 112 on a power supply line frombreaker 107 between circuit breaker 107 and the load 114 causes faultcurrent 109 to flow from the three generators 102 through circuitbreakers 104 through the low resistivity section to the high resistivitysection 106. The fault current then flows from the high resistivitysection 106 through circuit breaker 105 through circuit breaker 107 tothe short circuit at 112. The high resistivity section of the bus 106has a resistivity twice that of the low resistivity section bus 108. Thehigh resistivity of the bus section 106 causes a voltage drop and anassociated fault current reduction as the fault current travels throughthe high resistivity section of the bus 106. Thus, by reducing thevoltage through resistive loss, the high resistivity section of the busreduces the amount of fault current that flows through breaker 107 tothe electrical short 112. In an illustrative embodiment, the higherresistivity section 106 enables the specification of a lower faultinterrupting current value (KAIC) for breaker 107 than would be requiredif a low resistivity bus section been used in place of the highresistivity power distribution section. In another illustrativeembodiment, the entire power distribution bus is made of highresistivity material such as steel and no lower resistivity materialsuch as copper is used. In another illustrative embodiment the lowerresistivity member is a cable.

Turning now to FIG. 2, FIG. 2 is a schematic depiction 200 ofcommutation voltage spikes 202 and voltage notches 206 are shownsuperimposed on an alternating current waveform 204. The spikes andnotches in the voltage waveform can be caused by the commutation ofdiode, transistors or silicon controlled rectifiers (SCRs) in a 6-pulseSCR direct current drive with an alternating current 3-phase input.

Turning now to FIG. 3, in another illustrative embodiment a plurality ofhigh resistivity power distribution members 308 are provided. In oneparticular embodiment the high resistivity refers to a resistivityhaving a resistivity of approximately twice the resistivity of copper.The high resistivity power distribution members 308 are cables having ahigher resistivity than copper are provided to supply power to analternating current variable speed motor drive 302. In anotherillustrative embodiment, the high resistivity power distribution membersare high resistivity buses. Three phase alternating current 301 isprovided by the plurality of high resistivity cables 308.

In another illustrative embodiment the high resistivity cables are madeof steel. The alternating current drive variable speed motor drive 302is represented in FIG. 3 in schematic form by silicon controlledrectifiers 307 or other variable speed drives or devices causingharmonic voltage and current disturbance, internal capacitor 318 and aninverter 310. In an illustrative embodiment the high resistivity cables308 in combination with the internal capacitance 318 of the alternatingcurrent drive provides a smoothing RC filter that filters out electricaldisturbances on the power distribution system. For example, theresistance of the cable and capacitance of the electrical devicereceiving the electrical power can be tuned to filter out electricaldisturbances on the electrical power above the service frequency of 5-60HZ, for example, 1000 Hz so that voltage spikes and notches above 1000Hz such as the voltage notches and voltage spikes at 10 KHz shown inFIG. 3 are filtered out. In another embodiment a frequency lower orhigher than 100 HZ is selected for filtering based on the resistance ofthe cable and capacitance of electrical device. Electrical disturbancescan include but are not limited to, voltage spikes and voltage notcheson the input of three phase alternating current voltages 301. Thesespikes and notches can be caused by disturbances such as commutation ina 6-pulse SCR drive. An illustrative embodiment provides a simple highresistivity cable or bus that can be retrofitted into existing powerdistribution systems or installed new power distribution systems toprovide current limiting and electrical disturbance filtering. Inanother embodiment, high resistivity members 308 provide power to anuninterruptible power supply (UPS) having an internal capacitance. Theresistive power distribution apparatus combines with capacitance in theUPS to smooth out voltage notches that cause the UPS to use batterypower when sensing the voltage notch as a power outage.

Turning now to FIG. 4 in another illustrative embodiment a powerdistribution apparatus 400, a cable is provided having a highresistivity center member 402 and a low resistivity outer member 404.The low resistivity outer member surrounds the high resistivity centermember. In a particular illustrative embodiment, as shown in FIG. 4, thelow resistivity outer member is wound around high resistivity member402, the low resistivity member forming an inductive coil. In anotherillustrative embodiment, the high resistivity center member 402 and thelower resistivity member 404 are surrounded by a layer of highresistivity material 406. The high resistivity center member 402, thelower resistivity outer member 404 and the high resistivity outer member406 are connected electrically at each end by connectors 408 and 409. Inanother illustrative embodiment, 400 is a bus.

As shown in FIG. 4, high resistivity member 402 provides a current pathbetween connectors 408 and 409. Low resistivity outer member 404 actslike an inductor and presents an inductance to input alternating power401. High resistivity member 402 acts like a resistance and presentsresistance to input alternating power 401. Connectors 408 and 409 ateach end of cable 400 electrically connect outer high resistivity member406 surrounding low resistivity member 404 and center high resistivitymember 402. High resistivity outer member 406 and high resistivitycenter member 402 form a flux path 410 for flux generated by currentflowing through low resistivity surrounding member 404. Low resistivityouter member 404 provides a current path 412 for 60 cycle power. Highresistivity center member provides a current path for high frequencyelectrical disturbance currents as discussed below with respect to FIG.5

The outer low resistivity member 404 of cable or bus 400 looks like aninductor to alternating current input power 401. High resistivity centermember 402 looks like a resistor to alternating current input power 401.Capacitance 318 is internal to power consuming electrical devices whichconsume power supplied through apparatus 400.

At 50-60 Hz inductor 404 presents reactance equal to jωL, whereL=inductance (Henrys) and ω=2πf, where f=frequency (Hz). Powerdistribution systems experience high frequency disturbances superimposedonto the electrical power at a service frequency, 50-60 Hz. In theUnited States many places in the world, the service frequency is 50 or60 Hz. In a particular embodiment, the high frequency disturbances aresuperimposed onto the electrical power at a 50 or 60 Hz servicefrequency. The electrical disturbances are substantially higher than 60Hz and range of 10-100 KHz and higher. In another embodiment, theservice frequency is another frequency, higher or lower than 60 Hz;however, the service frequency is still substantially lower than thefrequency of electrical disturbances.

At 50-60 Hz the inductance presented by low resistivity surroundingmember 404 presents a reactance=jωL which presents a relatively lowresistance path to 60 Hz input current supplied by input power 401. Atthe higher frequencies for electrical disturbances, however, theinductance presented by low resistivity surrounding member 404represents a large reactance. Thus, the high frequency current forelectrical disturbances is routed largely through resistor 402 andincurs a voltage drop across resistor 402 and an associated drop incurrent reaching load 508.

Turning now to FIG. 5, a flow chart 500 showing functions performed inanother illustrative embodiment is depicted. An illustrative embodimentreceives electrical power on a low resistivity power distribution member504 and delivers the electrical power on a high resistivity powerdistribution member 506.

Turning now to FIG. 6, a flow chart 600 showing functions performed inanother illustrative embodiment is depicted. As shown in FIG. 6, anotherillustrative embodiment at 604 presents an inductive low resistivityouter member that presents a high reactance to high frequency electricaldisturbances on the electrical power and routes the electricaldisturbances through a high resistivity center member. The electricalpower at 50 or 60 Hz is routed through the high resistivity centermember 606.

In another illustrative embodiment, the high resistivity member and thelow resistivity member can be plated with another material such as tinto reduce corrosion between on the high resistivity member and the lowresistivity member. In another illustrative embodiment, the highresistivity member is steel plated with tin and low resistivity memberis copper plated with tin.

The illustrations of embodiments described herein are intended toprovide a general understanding of the structure of various embodiments,and they are not intended to serve as a complete description of all theelements and features of apparatus and systems that might make use ofthe structures described herein. Many other embodiments will be apparentto those of skill in the art upon reviewing the above description. Otherembodiments may be utilized and derived there from, such that structuraland logical substitutions and changes may be made without departing fromthe scope of this disclosure. Figures are also merely representationaland may not be drawn to scale. Certain proportions thereof may beexaggerated, while others may be minimized. Accordingly, thespecification and drawings are to be regarded in an illustrative ratherthan a restrictive sense.

Such embodiments of the inventive subject matter may be referred toherein, individually and/or collectively, by the term “invention” merelyfor convenience and without intending to voluntarily limit the scope ofthis application to any single invention or inventive concept if morethan one is in fact disclosed. Thus, although specific embodiments havebeen illustrated and described herein, it should be appreciated that anyarrangement calculated to achieve the same purpose may be substitutedfor the specific embodiments shown. This disclosure is intended to coverany and all adaptations or variations of various embodiments.Combinations of the above embodiments, and other embodiments notspecifically described herein, will be apparent to those of skill in theart upon reviewing the above description.

The Abstract of the Disclosure is provided to comply with 37 C.F.R.§1.72(b), requiring an abstract that will allow the reader to quicklyascertain the nature of the technical disclosure. It is submitted withthe understanding that it will not be used to interpret or limit thescope or meaning of the claims. In addition, in the foregoing DetailedDescription, it can be seen that various features are grouped togetherin a single embodiment for the purpose of streamlining the disclosure.This method of disclosure is not to be interpreted as reflecting anintention that the claimed embodiments require more features than areexpressly recited in each claim. Rather, as the following claimsreflect, inventive subject matter lies in less than all features of asingle disclosed embodiment. Thus the following claims are herebyincorporated into the Detailed Description, with each claim standing onits own as a separately claimed subject matter.

1. An electrical power distribution apparatus, the apparatus comprising:a first low resistivity power distribution member section for receivingelectrical power from a power supply; and a second high resistivitypower distribution member section having a resistivity higher than thefirst section and electrically connected to the first section forsupplying the electrical power to an electrical device, wherein thefirst power member section provides a first current path for lowerfrequency currents and a high reactance to higher frequency currents andwherein the second power distribution member provides a second currentpath for the higher frequency currents.
 2. The apparatus of claim 1,wherein the electrical device in electrical communication with thesecond section, wherein the second section reduces a current to theelectrical device.
 3. The apparatus of claim 2, wherein the electricaldevice is an electrical circuit breaker receiving power from the secondsection during an electrical short circuit on a load side of theelectrical circuit breaker.
 4. The apparatus of claim 1, wherein thefirst section has a resistivity of approximately one half of theresistivity of the second section.
 5. The apparatus of claim 1, whereinthe first section is made of copper and the second section is made ofsteel.
 6. The apparatus of claim 1, wherein the first section and thesecond section have resistivity approximately equal to twice theresistivity of copper.
 7. The apparatus of claim 1, wherein at least oneof the first section and the second section is a bus.
 8. The apparatusof claim 1, wherein at least one of the first section and the secondsection is a cable.
 9. The apparatus of claim 1, wherein the sectionforms an electrical filter with a capacitance of the electrical devicefor smoothing electrical disturbances in the electrical power suppliedto the electrical device.
 10. The apparatus of claim 9, wherein theelectrical device is a device selected from the group consisting of anuninterruptible power supply and an alternating current drive for avariable speed alternating current motor.
 11. The apparatus of claim 9,wherein the electrical disturbances are one selected from the groupconsisting of a voltage spike and a voltage notch.
 12. The apparatus ofclaim 1, wherein the second section comprises a center section and thefirst section comprises a low resistivity outer member surrounding thecenter member, wherein the low resistivity member forms an inductoraround the center member so that the low resistivity member presents ahigh reactance to high frequency voltages substantially higherthan50-60Hz, so that the high frequency currents pass through the centermember and experience a current reducing voltage loss.
 13. The apparatusof claim 12, wherein low frequency electrical power of approximately50-60Hz sees a low reactance on the low resistivity outer member andtravels through the inductor low resistivity outer member.
 14. Theapparatus of claim 12, wherein the low resistivity outer member has aresistivity of substantially one half the resistivity of the highresistivity center member.
 15. The cable of claim 13, wherein the lowresistivity outer member is made of copper and the high resistive centermember is made of steel.
 16. The apparatus of claim 12, furthercomprising: an outer high resistivity member surrounding the lowresistivity member and the center member.
 17. The apparatus of claim 16,further comprising a conductive connector at each end of the cable,wherein the conductive connectors form an electrical connection betweenthe high resistivity center member, the outer low resistivity member andthe outer high resistivity member, wherein low frequency current atsubstantially 60 Hz flows through the outer lower resistivity member andhigh frequency currents above 1 KHz flow though the high resistivitycenter member.
 18. The apparatus of claim 17, wherein the highresistivity center member and the high resistivity outer member form amagnetic flux path for magnetic flux generated by current flowing in thelow frequency surrounding member.
 19. An electrical power distributionapparatus comprising a first power distribution: member section forreceiving electrical power from a second high resistivity power:distribution member section having a resistivity higher than the firstsection and electrically connected an electrical device in electricalcommunication with the second section wherein the first power membersection provides a first current path for lower frequency currents and ahigh reactance to higher frequency currents and wherein the second powerdistribution member provides a second current path for the higherfrequency currents.
 20. The apparatus of claim 19, further wherein thesecond section comprises a center member and the first section comprisesa low resistivity outer member surrounding the center member.